/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You under the Apache License, Version 2.0
    * (the "License"); you may not use this file except in compliance with
    * the License.  You may obtain a copy of the License at
    *
    *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.commons.mail.resolver;
  
  import org.apache.commons.mail.DataSourceResolver;
  
  import javax.activation.DataSource;
  import java.io.IOException;
  
  /**
   * A composite data source resolver. It allows to resolve data sources coming from
   * multiple locations such as the classpath, the file system or an URL.
   *
   * @since 1.3
   */
  public class DataSourceCompositeResolver extends DataSourceBaseResolver
  {
      /** the list of resolvers */
      private final DataSourceResolver[] dataSourceResolvers;
  
      /**
       * Constructor.
       *
       * @param dataSourceResolvers a list of of resolvers being used
       */
      public DataSourceCompositeResolver(final DataSourceResolver[] dataSourceResolvers)
      {
          this.dataSourceResolvers = new DataSourceResolver[dataSourceResolvers.length];
          System.arraycopy(dataSourceResolvers, 0, this.dataSourceResolvers, 0, dataSourceResolvers.length);
      }
  
      /**
       * Constructor.
       *
       * @param dataSourceResolvers a list of of resolvers being used
       * @param isLenient shall we ignore resources not found or throw an exception?
       */
      public DataSourceCompositeResolver(final DataSourceResolver[] dataSourceResolvers, final boolean isLenient)
      {
          super(isLenient);
          this.dataSourceResolvers = new DataSourceResolver[dataSourceResolvers.length];
          System.arraycopy(dataSourceResolvers, 0, this.dataSourceResolvers, 0, dataSourceResolvers.length);
      }
  
      /**
       * Get the underlying data source resolvers.
       *
       * @return underlying data source resolvers
       */
      public DataSourceResolver[] getDataSourceResolvers()
      {
          // clone the internal array to prevent external modification (see EMAIL-116)
          final DataSourceResolver[] resolvers = new DataSourceResolver[dataSourceResolvers.length];
          System.arraycopy(dataSourceResolvers, 0, resolvers, 0, dataSourceResolvers.length);
          return resolvers;
      }
  
      /** {@inheritDoc} */
      @Override
      public DataSource resolve(final String resourceLocation) throws IOException
      {
          final DataSource result = resolve(resourceLocation, true);
  
          if (isLenient() || result != null)
          {
              return result;
          }
          throw new IOException("The following resource was not found : " + resourceLocation);
  
      }
  
      /** {@inheritDoc} */
      @Override
      public DataSource resolve(final String resourceLocation, final boolean isLenient) throws IOException
      {
          for (int i = 0; i < getDataSourceResolvers().length; i++)
          {
              final DataSourceResolver dataSourceResolver = getDataSourceResolvers()[i];
              final DataSource dataSource = dataSourceResolver.resolve(resourceLocation, isLenient);
  
              if (dataSource != null)
              {
                  return dataSource;
              }
          }
 
         if (isLenient)
         {
             return null;
         }
         throw new IOException("The following resource was not found : " + resourceLocation);
     }
 }